/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package cn.edu.thu.laud.objectstore;

import org.apache.cassandra.thrift.ConsistencyLevel;

/**
 * Class that is used similar to a transaction to set the consistency level for
 * a given operation. If none is set on the thread, ConsistencyLevel.ONE is used as the default
 * 
 * 
 * @author zhuoan
 * 
 */
public class CassandraConsistency {

	private static final ThreadLocal<ConsistencyLevel> level = new ThreadLocal<ConsistencyLevel>();
	
	private static ConsistencyLevel defaultLevel;

	
	static {
		defaultLevel = ConsistencyLevel.QUORUM;
	}
	
	/**
	 * Set the default level if it hasn't been set
	 * @param c
	 */
	public static void setDefault(ConsistencyLevel c){
		defaultLevel = c;
	}
	/**
	 * Set the consistency level for this thread
	 * 
	 * @param c
	 */
	public static void set(ConsistencyLevel c) {
		level.set(c);
	}

	/**
	 * Convenience wrapper for set(null)
	 */
	public static void remove() {
		set(null);
	}

	/**
	 * Get the currently set consistency level;
	 * 
	 * @return
	 */
	public static ConsistencyLevel get() {
		ConsistencyLevel l = level.get();

		if (l == null) {
			return defaultLevel;
		}

		return l;
	}

}
